docs: def swappable_setting(app_label, model):
      """
      Returns the setting name to use for the given model (i.e. AUTH_USER_MODEL)
      """
      prefix = _prefixes.get(app_label, app_label)
      setting = "{prefix}_{model}_MODEL".format(
          prefix=prefix.upper(),
          model=model.upper()
      )
  
      # Ensure this attribute exists to avoid migration issues in Django 1.7
      if not hasattr(settings, setting):
          setattr(settings, setting, join(app_label, model))
  
      return setting